Device for cleaning the collecting electrodes in electrostatic precipitators



Aug. 4, 1965 s. GUSTAFSSON ETAL 3,201,923

DEVICE FOR CLEANING THE COLLECTING ELECTRODES IN ELECTROSTATICPRECIPITATORS 2 Sheets-Sheet 1 Filed Oct. 20, 1960 4, 1965 s. GUSTAFSSONETAL 3,201,923

DEVICE FOR CLEANING THE COLLECTING ELECTRODES IN ELECTROSTATICPRECIPITATORS 2 Sheets-Sheet 2 Filed Oct. 20, 1960 United States Patent3,201,923 DEVICE FOR CLEANING THE CQLLECT- ING ELECTRODES INELECTROSTATIC PRECIPITATORS Stig Gnstafsson, Jonkoping, and GlistaMildh, Vattersnas,

Sweden, assignors to Aktiebolaget 'Svenska Flaktfabriken, Nacka, SwedenFiled Oct. 20, 1960, Ser. No. 63,874 Claims priority, applicationSweden, Jan. 30, 1960, 935/60 2 Claims. (Cl. 55-112) The presentinvention relates to a device for cleaning electrostatic precipitatorsin which the collecting electrodes are in the form of a plurality ofside-by-side rows of preferably plate-shaped electrode elements parallelto the direction of gas flow. The electrode elements in each row arepivotally suspended in tandem relationship. The device includes impactbars disposed beneath the electrodes and carried by the same, and whichare arranged to be actuated by hammers mounted on a rotatable shaftextending transversely to the direction of gas flow to thereby impart tothe electrode elements an oscillatory movement in the direction of thegas flow.

In prior art arrangements of the kind referred to, upstanding U-shapedguide brackets have been mounted on laterally-extending rails rigidlysecured at their opposite ends to the walls of the electrofilter toprovide guiding units for guiding the impact bars against lateralmovement. However, due to the difference in heating of the guiding unitson one hand, and the filter casing on the other, a diiference in thermalexpansion has occurred which has caused bending or displacement of theguiding units. Therefore, in conjunction with mounting the guide railsin the walls, it has been necessary to dispose the rails so as toprovide ample clearance between the bottom edge of the impact bars andthe top edge of the guide rails to thereby alford sufficient freedom forthermal expansion of the collecting electrodes. Because of this, it hasbeen necessary to make the upright legs of the guide bracketsunreasonably long whereby the voltage gaps between the legs and theemission frame became critical and whereby the breaking stress at theanchor points between the brackets and the rails caused reduction of themechanical strength. Sometimes when the clearance between the bottomedge of the impact bars and the top edge of the guide rails was toosmall,

the expansion of the collecting electrodes has caused their upper endsto become disconnected from their suspension mountings, resulting in acomplete breakdown or collapse of the precipitator.

It is an object of the present invention to eliminate these drawbacks.To this end, in accordance with the present invention, the impact barsare guided against lateral movement by U-shaped guide brackets mountedon laterally-extending rails which are disposed at the ends of theelectrode rows and are secured to, and carried by, the two outermostimpact bars.

Another important feature of the present invention is the provision ofbaffle plates depending from the laterally-extending rails to preventany substantial amount of gas from flowing longitudinally in the spacebeneath the electrodes.

The invention will now be described in greater detail with reference tothe accompanying drawings in which:

FIG. 1 is a fragmentary longitudinal vertical section with portionsbroken away through an electrostatic precipitator embodying a cleaningdevice in accordance with the present invention;

FIG. 2 is a fragmentary transverse vertical section with portions brokenaway taken along the line 2-2 of FIG. 1;

3,201,923 Patented Aug. 24, 1965 FIG. 3 is a fragmentary perspectiveview showing two impact bars and their associated collecting electrodes(one being removed) and the intermediate emission electrodes; and

FIG. 4 is a view in side elevation with portions broken away of anelectrostatic precipitator embodying the present invention.

Referring now to the drawings, the electrostatic precipitator 1comprises a casing 2 having an inlet 2a and and outlet 2b. Within thecasing are a plurality of plate-shaped collecting electrodes 3 arrangedparallel to the direction of gas flow in a series of transversely-shapedlongitudinal rows As shown in FIG. 4, the electrodes 3 are mounted forswinging movement as indicated at 3a in a suspension mounting 3badjacent the top wall of the casing 2. Intermediate the adjacent rows ofcollecting electrodes 3 are longitudinal rows of discharge electrodes16, in the present instance in the form of rods (see FIGS. 2 and 3).

For cleaning the electrodes, the electrostatic precipitator includes acleaning device which consists of a number of impact bars 4 arranged tobe engaged by hammers 6 mounted on a rotary shaft 5 extendingtransversely across the casing. In the present instance, the shaft 5 ismounted in journals 5a supported on standards 5b projecting inwardlyfrom the wall of the casing 2. As shown in FIG. 2, the shaft 5 isrotated by a sprocket 14 adapted to receive a chain from a drive' motor(not shown). The hammers 6, upon rotation of the shaft 5, swing againstthe impact bars 4 substantially as shown in US. Patent No. 2,864,459 toGustafsson. The impact bars 4 are provided with a plurality of studs 7along their length adapted to engage against lugs 25 depending from theelectrodes 3. There is an impact bar for each longitudinal row ofcollecting electrodes 3 and it is carried by the outermost electrodes ineach row by means of supporting pins 9 projecting laterally from thelugs 8a of the outermost electrodes. As shown in FIGS. 1 and 3, thesupporting pins 9 underlie the impact bars 4 to provide the solevertical support therefor.

In accordance with the invention, the impact bars 4 and the electrodes3, are guided against lateral movement by U-shaped guide brackets 10which in the present instance, comprise a pair of upstanding legs 10amounted on laterally-extending tubular rails 11. The rails 11 aredisposed at the ends of the rows of electrodes and are secured to thetwo outermost impact bars, for example by angles lla, so that theoutermost bars 4 serve as the sole support for the rail 11.

In the embodiment shown in the drawings, the laterally-extending rails11 are provided with depending baffie plates 12 which prevent anysubstantial amount of gas introduced into the electrostatic precipitatorto be purified from flowing longitudinally Within the space beneath theelectrodes.

Where the electrostatic precipitator has substantial width, thelaterally-extending rails 11 are preferably divided into a plurality offlexibly interconnected rail sections, each section being carried by theimpact bars. To this end, a joint and spacing member 13 is provided tointerconnect two adjacent rail sections, 538 shown in FIG. 2.

While a particular embodiment of the present invention has been hereinillustrated and described, it is not intended to limit the invention tosuch disclosure, but changes and modifications may be made therein andthereto within the scope of the following claims:

What we claim is:

1. An electrostatic precipitator comprising:

a casing arranged for horizontal gas flow therethrough,

plate-shaped collecting electrodes disposed parallel to and arranged.intranswhich are, parallel an elongatedimpact bar underlying eachrow ofelectrodes and coextensive therewith;

' hammer means within said casing for each'impact bar' operableupon'actuation thereof to engage and dis-. place said bar longitudinallyin the direction of gas flow through said precipitator,

abutment means on said, impact bar engaging each 1' of said electrodesin the associated row to effect oscillatory movement of said electrodes"in the di-' rection of gas flow upon actuation of said hammer means, and'in'cluding means at each end of *each for swingimpact bar to suspendsaid bar from" said outermost electrodes,

laterally extending rails adjacent the ends of'the rows of electrodes,a'nd means at each end of each rail;

securing said rail to the impact bar adjacent each end to suspend therail therefrom, said means being the sole support for said rails,

a U-shaped guide bracket mounted on said 'rail to embrace each impact'bar and guide it against lateral movement while permitting free.thermal expansion of said collecting electrodes,.and battle plates secured to and depending from said laterally extending rails and operableto prevent any substantial amount a of the gas from flowinglongitudinally within the space beneath the electrodes. 2. Apparatusaccording to claim 1 wherein said laterally-extending rails, at each'endof the impact bars are divided into a plurality of aligned separate rail"sections; each suspended from two impact bar s adjacent 7 itsends,randi including flexible connecting- 7 connecting said trailsections. 1

means inter- 1 References Cited by the Examiner UNITED "STATES PATENTS1,882,949 10/32 Ruder, V 2,595,204 4/52 Richardson 55-112 7 2,703,6303/55- CroWder ss 300 2312035; 11/57 Sohlmanet a1; 55-430 X2,864,459J12/58, Gustafsson 55-7108 X FOREIGN PATENTS 75143737 1152Belgium. 509,898 '11/20' France.

373,773 4/23 Germ-any. 450,391 10/27 -Germany. 7 437, 20 11 35" GreatBritain. 4

790,130 "258 Great Britain; HARRY B; THORNTioN,-Primaryr Examiner. I

WALTER BERLOWITZ,

1. AN ELECTROSTATIC PRECIPITATOR COMPRISING: A CASING ARRANGED FORHORIZONTAL GAS FLOW THERETHROUGH, PLATE-SHAPED COLLECTING ELECTRODESDISPOSED PARALLEL TO THE DIRECTION OF GAS FLOW AND ARRANGED INTRANSVERSELY-SPACED LONGITUDINAL ROWS WHICH ARE PARALLEL TO THE GASFLOW, MEANS SUSPENDING SAID COLLECTING ELECTRODES FOR SWINGING MOVEMENTIN SAID CASING, AN ELONGATED IMPACT BAR UNDERLYING EACH ROW OFELECTRODES AND COEXTENSIVE THEREWITH, HAMMER MEANS WITHIN SAID CASINGFOR EACH IMPACT BAR OPERABLE UPON ACTUATION THEREOF TO ENGAGE ANDDISPLACE SAID BAR LONGITUDINALLY IN THE DIRECTION OF GAS FLOW THROUGHSAID PRECIPITATOR, ABUTMENT MEANS ON SAID IMPACT BAR ENGAGING EACH OFSAID ELECTRODES IN THE ASSOCIATED ROW TO EFFECT OSCILLATORY MOVEMENT OFSAID ELECTRODES IN THE DIRECTION OF GAS FLOW UPON ACTUATION OF SAIDHAMMER MEANS, AND INCLUDING MEANS AT EACH END OF EACH IMPACT BAR TOSUSPEND SAID BAR FROM SAID OUTERMOST ELECTRODES, LATERALLY EXTENDINGRAILS ADJACENT THE ENDS OF THE ROWS OF ELECTRODES, AND MEANS AT EACH ENDOF EACH RAIL SECURING SAID RAIL TO THE IMPACT BAR ADJACENT EACH END TOSUSPEND THE RAIL THEREFROM, SAID MEANS BEING THE SOLE SUPPORT FOR SAIDRAILS, A U-SHAPED GUIDE BRACKET MOUNTED ON SAID RAIL TO EMBRACE EACHIMPACT BAR AND GUIDE IT AGAINST LATERAL MOVEMENT WHILE PERMITTING FREETHERMAL EXPANSION OF SAID COLLECTING ELECTRODES, AND BAFFLE PLATESSECURED TO AND DEPENDING FROM SAID LATERALLY EXTENDING RAILS ANDOPERABLE TO PREVENT ANY SUBSTANTIAL AMOUNT OF THE GAS FROM FLOWINGLONGITUDINALLY WITHIN THE SPACE BENEATH THE ELECTRODES.